Refining element of a disc refiner

ABSTRACT

A refining element is disclosed for use in a disk refiner having a refining element holder surface including a plurality of attachment holes, the refining element including a plurality of working members on its front surface and a rear surface adapted to be attached to the refining element holder, the refining element further includes a plurality of attachment through holes extending through the refining element for attachment to the refining element holder at corresponding attachment holes therein, whereby attachment screws can be provided for affixing the refining element to the refining element holder through the plurality of attachment through holes, and at least one removal hole including threads and being substantially centrally located on the refining element, whereby the refining element can be removed from the refining element holder by extending a removal screw through the removal hole to apply pressure for removal of the refining element against the refining element holder.

FIELD OF THE INVENTION

This present invention relates to a refining element for disk refiners.The present element invention also relates to such refining elementsprovided on their front side with working members for defibering andrefining lignocellulose-containing fiber material. The refining elementfurther is formed with through holes for attaching it on a holder in therefiner by means of screws.

BACKGROUND OF THE INVENTION

In using refining elements on such disk refiners, a plurality of suchrefining elements are attached to the refiner in the form of a ringabout each of two opposed holders, which are rotary relative to eachother. Both holders can be rotated in opposed directions, or one holdercan be rotary and one stationary.

During refining, the material to be refined passes through the refininggap, which is formed between refining elements on the opposed holders.During said passage, the material is simultaneously worked. This workingnormally takes place during continuous operation under high pressure andtemperature, whereby the working members on the front sides of therefining elements are subjected to wear. Due to such wear, the qualityof the worked fiber material deteriorates, so that the refining elementsmust be exchanged after a certain period of time. This time can amountto several months.

During the necessary exchange of the refining elements, it has beenfound that the old elements have become so rigidly stuck, due to bakedfibers and extracted substances, that they can be removed only withgreat trouble and after a long period of time. In many cases it is notsufficient to merely loosen the holding screws. Since the refiningelements are fixed very tightly on the holder, there is no space forremoving them by prying. In certain cases it has thus been necessary toknock off or cut to pieces one of the elements in order to be able toremove the elements, which moreover involves the risk of accidents.After one of the elements has been removed, it is then relatively simpleto take off the remaining elements.

SUMMARY OF THE INVENTION

In accordance with the present invention, the aforementioned problemshave now been solved by the invention of a refining element for use in adisk refiner having a refining element holder surface including aplurality of attachment holes thereon, the refining element comprising afront surface and a rear surface, the front surface including aplurality of working members and the rear surface adapted for attachmentto the refining element holder, the refining element further comprisinga plurality of attachment through holes extending through the refiningelement for attaching the refining element to the refining elementholder at corresponding attachment holes therein, whereby attachmentsscrews can be provided for affixing the refining element to the refiningelement holder through the plurality of attachment through holes, and atleast one removal hole, the removal hole including threads and beingsubstantially centrally located on the refining element whereby therefining element can be removed from the refining element holder byextending a removal member through the removal hole to apply pressurefor removal of the refining element against the refining element holder.

In accordance with one embodiment of the refining element of the presentinvention, the plurality of working members on the front surface of therefining element comprise a plurality of bar members.

In accordance with another embodiment of the refining element of thepresent invention, a covering screw is provided for application to theremoval hole for filling the removal hole during use of the refiningelement in the disk refiner.

In accordance with a preferred embodiment of the refining element of thepresent invention, the refining element can be removed from the refiningelement holder by removing the covering screw, and wherein the removalmember comprises a removal screw having a length greater than thethickness of the refining element.

In accordance with another embodiment of the refining element of thepresent invention, the length of the covering screw is less than thethickness of the refining element, and the covering screw includes ahead portion. Preferably, the length of the covering screw is less thanthe thickness of the refining element by a distance of between about 1and 3 mm, and the head portion of the covering screw is located betweenabout 1 and 3 mm below the front surface of the refining element.

The present invention thus provides for the design of a refining elementwhich makes it possible to rapidly and simply remove refining elementsfrom a holder in a disk refiner with satisfactory safety for both staffand the equipment itself.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be more fully appreciated with reference tothe following detailed description, which, in turn, makes reference tothe Figures in which:

FIG. 1 is a top, elevational view of a refining segment in accordancewith the present invention;

FIG. 2 is an enlarged front view of a portion of the refining elementshown in FIG. 1; and

FIG. 3 is a side view of the portion of the refining element shown inFIG. 2 taken along section A--A thereof.

DETAILED DESCRIPTION

The refining element 1 shown in FIG. 1 is formed on its front side withworking embers in the form of bars 2 with intermediate grooves 3.Through holes 4, usually three in number, are provided for attaching theelement on the holder in the disk refiner. These holes are located sothat good abutment to the holder is obtained. The attachment is carriedout by the screws, which are tightened from the front side intocorresponding threaded holes in the holder.

The refining element 1 is further provided with a threaded hole 5located centrally on the refining element, preferably close to itscenter of gravity. About the hole 5 a zone 6 without bars is located. Inthreaded hole 5 a covering screw 7 is attached in such a manner, thatthe zone 6 about the hole provides sufficient contact surface for thehead of the covering screw 7 to be locked against the material in therefining element 1. Normally one single threaded hole 5 is sufficient,but it is, of course, possible to have two or more threaded holes. Insuch cases, a covering screw is to be attached in every such threadedhole.

The head of the covering screw 7 is formed so that it is locatedpreferably 1-3 mm beneath the working surface of the bars 2. The screwhead preferably is formed for an internal hexagon spanner. The coveringscrew 7 extends only just through the refining element, and in operationsits in the hole 5 in order to prevent fibers from penetrating betweenthe refining element and the holder. When the refining element is to beremoved, first the attachment screws are loosened. They are not,however, entirely threaded out of the holes in the holder. The coveringscrew 7, however, is screwed out of the hole 5. Thereafter a longerscrew, a bursting screw, is screwed into the hole 5. When this burstingscrew arrives at the holder lying behind the refining element, it liftsthe refining element up from the holder with continued screwing. Theforce achievable in this has been found to be sufficient for rapidly andsimply loosening the refining element, which otherwise could not beloosened without great problems, as set forth above. The remainingattachment screws prevent the refining element from flying off in anuncontrolled manner when loosened from the holder.

Alternatively, the threaded hole 5 can be used for pulling out therefining element. In this case the attachment screws are screwed outentirely. A clamp can be attached by means of long screws, which extendthrough attachment holes 4 of the refining element and are tightened inthe holder. By means of this clamp and a longer screw to be attached inthe threaded hole 5, the refining element can thereafter be pulled out.The clamp in this case prevents the refining element from flying off ifit loosens abruptly.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

We claim:
 1. A refining element for use in a disk refiner having arefining element holder surface including a plurality of attachmentholes thereon, said refining element comprising:a front surface and arear surface, said front surface including a plurality of workingmembers and said rear surface adapted for attachment to said refiningelement holder, said refining element further comprising a plurality ofattachment through holes extending through said refining element forattaching said refining element to said refining element holder atcorresponding attachment holes therein, attachment screws provided foraffixing said refining element to said refining element holder throughsaid plurality of attachment through holes, at least one removal holelocated within said refining element, a covering screw for filling saidremoval hole during use of said refining element in said disk refiner,said covering screw having a length less than the thickness of saidrefining element, a removal screw having the length greater than thethickness of said refining element, whereby said refining element can beremoved from said refining element holder by removing said coveringscrew and extending said removal screw through said removal hole toapply pressure for removal of said refining element against saidrefining element holder.
 2. The refining element of claim 1 wherein saidplurality of working members on said front surface of said refiningelement comprise a plurality of bar members.
 3. The refining element ofclaim 1 wherein said length of said covering screw is less than thethickness of said refining element by a distance of between about 1 and3 mm, whereby said head portion of said covering screw is locatedbetween about 1 and 3 mm below the said front surface of said refiningelement.
 4. The refining element of claim 1, wherein said removal holeincludes threads and is centrally located within said refining elementand said covering screw is formed with a head portion.
 5. The refiningelement of claim 4, wherein said head portion is formed with an internalhexagon area.